Multiply paper bag

ABSTRACT

A multiply paper bag in which the inner wall of the inner ply is coated with a heat sealable moistureproof material and the end of the bag is folded, sealed and taped to form a leakproof closure. Apparatus for the manufacture of such bags having means for advancing bag blanks one after the other along a path, means along the path for heating the bottom end of the blank to soften the thermoplastic coating, means for applying a sealing force to the softened thermoplastic coating, means for holding the seal while the thermoplastic coating cools and hardens, means for embossing the bag blank along a fold line for folding the bag blank end along the fold line and for folding the folded portion into the sidewall of the blank and means for applying, coating and adhesively securing a tape to the folded portion and the sidewall of the blank.

United States Patent inventors Appl. No. Filed Patented AssigneeMULTIPLY PAPER BAG 10 Claims, 47 Drawing Figs.

US. Cl 229/57,

Int. Cl. B6511 33/02 Field of Search 229/57, 55, l 62; 93/8, 62

{111 3,567,1lll

Primary Examiner-David M. Bockenek Attorney-Charles B. Smith ABSTRACT: Amultiply paper bag in which the inner wall of the inner ply is coatedwith a heat scalable moistureproof material and the end of the bag isfolded, sealed and taped to form a leakproof closure. Apparatus for themanufacture of such bags having means for advancing bag blanks one afterthe other along a path, means along the path for heating the bottom endof the blank to soften the thermoplastic coating, means for applying asealing force to the softened thermoplastic coating, means for holdingthe seal while the thermoplastic coating cools and hardens, means forembossing the bag blank along a fold line for folding the bag blank endalong the fold line and for folding the folded portion into the sidewallof the blank and means for applying, coating and adhesively securing atape to the folded portion and the sidewall of the blank.

PATENTEB MAR 2 l9?! SHEET 02 0F 14 SHEET PATENTED MR 2 Ian SHEETPATENTED MAR 2 I971 PATENTED mm m SHEET 1 1 [JF PATENTED MAR 2 IHYISHEET 12 HF PATENTED MAR 21m SHEET 1B OF 14 MULTIIIP'LY PAPER BAGIeakproof closure and to apparatus for the manufacture of such bags.

The use of paper bags for the disposal of garbage, trash, rubbish andrefuse from homes, hospitals, institutions, and the like, has manyadvantages. In many areas, local health and sanitation ordinancesrequire that garbage and trash be wrapped. Such wrapping, among otherthings eliminates soiled cans, the banging and hammering of the cans,easier handling of the garbage and rubbish, and has a number of other advantages. Mere wrapping of the garbage and rubbish does not, however, inallinstances attain such advantages because, if the wrapping opens up orfails before the garbage and trash is collected and disposed, theseadvantages are not always attained. Thus, in some areas, particularly inhospitals and institutions disposable, waterproof containers arespecified for garbage, trash and waste. In addition to being waterproof,such containers must also have certain strengths so that, when filled,the container will not rip, open up or fail and spill its contents andso that, when filled, the container might be handled, such as in thehandling required in picking up and, disposing of the filled containerin an incinerator, or the like.

Various attempts have, heretofore, been made to provide an acceptablecontainer for garbage, trash and the like. Such containers have includedan inner paper ply coated on its inner surface so that the inner surfaceis waterproof and an outer ply treated with a material to render theouter surface repellent to atmospheric moisture, such as rain, snow andthe like. One of the difficulties heretofore encountered in the makingof such containers has been to provide an enclosure which is waterproofand sufficiently strong to support the weight of the garbage, trash andwaste and handling. Some of such bags, in order to attain the necessarystrength, have been sewed or stitched. Because such sewing andstitchingrequires perforation of the various plies and, at suchperforations, have exposed the paper to wicking and wetting either fromthe interior or exterior of the bag, such bags, where the ends are sewn,have not been completely satisfactory. Furthermore, the sewing orstitching of the end closure has added to the cost of the bag.

The instant invention is concerned with an improved paper bag forgarbage, trash and waste in which the bottom end of the bag is heatsealed, creased and folded and a tape of predetermined length is appliedto the end of the bag over the end of the folded portion to reinforcethe end closure and prevent wicking or wetting of the bottom through theexposed edges of the plies. In heat sealing the end prior to creasingand folding, the opposite walls of the inner ply are sealed along a linewhich, when the bag is folded, is along a line extending widthwise ofthe bag spacedupwardly of the folded portion away from the fold line.Thus, at the fold line, where the bottom of the bag is creased, theinner wall of the inner ply, at the creased line, can expand withoutrupturing, tearing,or breaking the waterproof coating on the innersurface of the inner ply. This is important because, as has been notedabove, wicking or wetting of the bag at the bottom weakens the bag endand results in ripping, tearing and rupturing of the bag bottom which,when it occurs, spills the bag's contents.

The instant invention is also concerned with a machine for producingsuch a bag. In the machine, the end of the bag is heated, softening thethermoplastic coating on the inner wall of the inner ply. After thecoating has been softened, the end of the bag is sealed along a linewhich, after the bag is folded will be between the fold crease and the.bag end. The bag, after it is sealed, is creased along a line above theseal line, away from the end, and the end is folded at the crease andthe tape is supplied over the fold end and adhesively secured over thefold edge.

The instant invention would be better understood from the followingdescription and appended drawings in which:

FIG. 1 is a perspective view, partially broken away, of a 2- ply sheetused in forming the bag of the instant invention;

FIG. 2 is a perspective view of the sheet of FIG. 1 formed into a tubewith the end open;

FIG. 3 is a perspective view of the bag of the instant invention withthe end sealed, creased, folded and the tape applied;

FIG. 4 is an end view of the tab tube of FIG. 2;

FIG. 5 is a side elevational view of the bag of the instant invention;

FIGS. 6 to 13 are top plan views of the bag at the various stages offormation of the bag end closure;

FIGS. 14a, b and c are side elevational views of the machine for makingthe bag'of the instant invention, a portion of the machine being shown,inside elevation in each of the FIGS.;

FIGS. 15a and 15b are top plan views, with sections broken away, of themachine of FIGS. 14a, b and 0;

FIG. 16 is a side elevational view, in enlarged detail, taken at line16-16, FIG. 15a;

FIG. 17 is a cross-sectional view taken at line 17-17, FIG. 16;

FIG. 18 is an enlarged end view, partly in section, taken at line 18-18,FIGL14a;

FIG. 19 is an enlarged end view, partly in section, taken at line 19-19,FIG. 14b;

FIG. 20 is a side elevational view, taken at line 20-20, FIG. 19;

FIG. 21 is a view, taken at line 21-21, FIG. 20;

FIG. 22 is a cross sectional view of the bag end, taken at line 22-22,FIG. 8;

FIG. 23 is a view, partially broken away and in section taken at line23-23, FIG.

FIG. 24 is a side elevational view taken at line 24-24, FIG. 23;

FIG. 25 is a view taken at line 25-25, FIG. 14c;

FIG. 26 is a side elevational view taken at line 26-26,.FIG. 25;

FIG. 27 is an enlarged end view, partly in section of the driving rollof FIG. 25;

FIG. 28 is an enlarged view of the bag taken at line 28-28, FIG. 9;

' FIG. 29 is a side elevational view taken at line 29-29, FIG. 15b;

FIGS. 30, 31, 32, 33 and 34 are views taken at lines 30-30, 31-31,32-32, 33-33 and 34-34, respectively, FIG. 29;

FIG. 35 is a view taken at line 35-35, FIG. 140;

FIG. 36 is a cross-sectional view of the bag end taken at line 36-36,FIG. 11;

FIG. 37 is an enlarged side elevational view of the tape applicationtaken at line 37-37, FIG. 15b,-

FIG. 38 is a view of the tape application rolls and knife taken at line38-38, FIG. 37;

FIG. 39 is a view of the tape guide taken at line 39-39, FIG. 37; a

FIG. 40 is a cross-sectional view of the tape guide taken at line 40-40,FIG. 39;

FIG. 41 is an enlarged view, in cross section, of the bag end' taken atline 41-40, FIG. 12; and

FIGS. 42, 43 and 44 are enlarged views, broken away, of the tapeapplicator rolls, knife and tape brake showing various positions of thetape applicator units at various stages of operation.

Referring to FIGS. 1, 2 and 4, the bag of the instant invention includesouter ply sheet 2 and inner ply sheet 4 of approximately the same lengthand width ovcrlayed, one over the other, with their longitudinal edgesstaggered so that, when longitudinally folded along lines 6, 8 and 10,and 12, 14 and 16 with longitudinal edges 2', 2" of outer ply sheet 2and iongitudinal edges 4', 4" of inner ply sheet 4 overlapped, theIongitudinal seams thus formed and adhesi'vely secured together, as on aconventional tubing machine, are staggered as best shown in FIGS. 2 andt.

The outer surface of outer ply sheet 2 which, when the sheets areoverlayed, one over the other, and longitudinally folded and seamed,forms the outer surface of the tubed plies is treated with a waterrepellent material so that, if exposed to the elements, such as rain,snow and the like, the outer surface of outer ply sheet 2 will shedwater. The inner surface of inner ply sheet 4 is coated with athermoplastic film, such as polyethylene, in a conventional manner. Incoating the inner surface of inner ply sheet 4, a heavy coating ofthermoplastic is not required, so long as the coating bars water fromreaching the paper for reasons more apparent hereinafter. Before innerply sheet 4 is laid over outer ply sheet 2, a water resistant adhesiveis applied to the inner surface of outer ply sheet 2 along adiscontinuous line of dots 18 about inch from the bottom edge of thesheet and blocks 20 about inch from the bottom. In addition, adiscontinuous line of dots 22 of water resistant adhesive is appliedabout 3 inches from the bottom edge of outer ply sheet 2 between foldline and the sheet edge and dots 24 between fold line 16 and the sheetedge. Because such adhesive is water resistant and the opposing faces ofsheets 2, 4 are wettable, when the sheets are brought together, theadhesive dots and blocks adhesively secure the sheets together and holdthe sheets in alignment for further handling.

Referring to FIGS. 14a, 14b, 14c and a and 15b, the ap paratus forproducing the closed end bag of the instant invention includes frame 32on which are mounted a heating section, generally designated 34, asealing section, generally designated 36, a creasing and foldingsection, generally designated 38, and a taping section, generallydesignated 40. Sprockets 42, 44 are keyed to shafts 46, 48 mounted forrotation, in suitable hearings, in supports 50, 52 on frame 32. At theopposite end of heating and sealing sections 34, 36, sprockets 54, 56are keyed to shafts 58, 60 mounted for rotation, in suitable bearings,in supports 62, 64. Chain 66 passes, in an endless loop, aroundsprockets 42, 54 and chain 68 passes, in a similar manner aroundsprockets 44, 56. For reasons more apparent hereinafter, bag supportingtable 70. FIGS. 15a and 15b, is supported on frame 32, in alignment withopposing chains 66, 68, and supports the bags as the bag ends areheated, sealed, folded and taped as such bags move from the left to theright of the machine as such machine is viewed in FIGS. 14a, 14b, 140,15a and 15b. The end of such bag is gripped between, and the bag is fedby, opposing chains 66, 68 in a manner later described and to assistchains 66, 68 in-feeding such bags and to maintain the ends of the bagsin alignment in the heating and sealing sections and parallel with eachother, such bags are supported on endless chain 72, projecting upwardthrough slot 74 in supporting table 70, chain 72 passing, at one of itsends, around sprocket 76 keyed to shaft 48 and, at its other end, aroundsprocket 78 keyed to shaft 60.

As best shown in FIGS. 14a, 14b, 16, 17 and 18, heater sec tion 34includes upper heater, generally designated 81) and lower heater,generally designated 82, mounted on frame 32 by a plurality of supports84 spaced substantially equidistant along frame 32. With particularreference to FIGS. 16, 17 and 18, upper chain guide 86 having fastenedthereto upper heater element stop 88 is mounted on bracket 90 fixed toone end of spring support 92, spring support 92 being fixed, at itsopposite end to support 84. Lower chain guide 94 is fixed to bracket 94having heater element support 96 affixed thereto is mounted on bracket98 attached to lower arm 100 of support 84, lower element 100 of support84 mounting such support on frame 32. Chain guide 94 guiding andsupporting chain 68 is rigidly mounted on support element 100 whilechain guide 86 of upper chain 66 is spring supported by spring support92. Thus, the opposing faces of chains 66, 68 are spring urged by leafspring support 92 toward each other thereby gripping the paper bagpositioned therebetween, as shown in phantom lines in FIG. 17. Upperheater head 102 having a downwardly pro.- jecting heat sink 104 and aheater unit, such as 106 extending axially along heater section 34 ismounted by support 108 on leaf spring 110, the end of leaf spring 110being fixed to clamp 112 fixed by clamping screw 114 to shaft 116 forreasons more apparent hereinafter. Heat shield 118 mounted on support108 extends around upper heater head 102. Lower heater head 120 havingupwardly extending heat sink 122 and a heater element, such aselectrical element 124 extending axially thereof is mounted by support126 on leaf spring 128 fastened at its opposite end to clamp 130 fixedby clamping screw 132 to shaft 134. Shafts 116 and 134 extend axiallyalong heater section 34 and are rotatably supported on supports 84 bybrackets 136.

As best shown in FIG. 18, gear 138 is fixed to shaft 116 and gear 140mating with gear 138 is fixed to shaft 134. Cylinder 141), FIG. 18, ispivotally mounted on frame 34 and piston rod 142 of cylinder 140 isconnected by clevis 144 to arm 146 clamped by clamping screw 148 toshaft 134. Cylinder 140 and piston 142 through arm 146 and mating gears138, 140 rotate shafts 116, 134 to rotate heater heads 102, 120 from theposition shown in full line in FIG. 17 to the position shown in phantomline and vice versa. When in full line position, the ends of springs110, 128 engage stops 88, 96, respectively, such stops, in cooperationwith leaf spring support 92 spacing heat sinks 104, 122 from theopposite sides of the paper bag passing therebetween.

Referring now to FIGS. 14b, 15a, 19, 20, 21 and 22, sealing section 36includes support 150 fixed to frame 32 and rotatably supporting matinggears 152, 154 and mating gears 156, 158 and idler gear 160 mountedbetween gears 154, 158. Gears 152, 154, 156, 158 are keyed,respectively, to shafts 162, 164, 166, 168, shafts 164, 168 beingrotatably supported, in fixed position on support 150 and shafts 162,164 being mounted, respectively, in blocks 170, 172 slidably mounted insupport 150 and urged downwardly, for reasons more apparent hereinafter,by springs 174, 176. Pressure wheels 178, are mounted on shafts 162,166, respectively, and sealing wheels 182, 184 are mounted on shafts164, 166, respectively.

Referring to FIG. 21, sealing wheels 182, 184 are identical each havingan inner element 186 fixed to the shaft by setscrew 188, outer element190 fixed to the shaft by setscrew 192 and intermediate element 194having an outer rounded surface 196 projecting outwardly beyond elements186, 190 and rotatably supported on the shaft by bearings 198, 200. Theouter surfaces of elements 186, 190 are knurled for reasons moreapparent hereinafter.

As best shown in FIGS. 14b, 14c, 15a, 15b, 23 and 24, endless belts 210,212 are driven, respectively, at one end, by belt pulleys 214, 216,keyed, respectively, to shafts 58, 60 and at their opposite ends, bybelt pulleys 218, 220, keyed, respectively, to shafts 222, 224. As bestshown in FIGS. 23, 24, but 212, intermediate pulleys 216, 220, issupported on rollers 226 and roller guides 228 and belt 210,intermediate pulleys 214, 228, is urged toward belt 212 by rollers 230and roller guides 232, mounted on the frame and urged toward belt 212 byspring 234.

Referring to FIGS. 14c, 15b, 25 and 26, upper embossing roll 240, havinga knurled or roughened surface 242 and embossing disc 244, having aradius slightly longer than the radius of embossing roll 240, aremounted on shaft 246, rotatably supported at its opposite ends, insupports 248, 250, spring urged by spring 251, downwardly toward spacedrollers 252, 254, having knurled or roughened surfaces, mounted on shaft256. As best shown in FIG. 27, embossing roll 240 is fixed to shaft 246by clamp 258 and screw 260. Embossing disc 244 is mounted for rotationon shaft 246 on hearing 262 and is urged by spring 264, FIG. 25, towardembossing roll 240. Thus, the outer end of disc 244 extending beyondroll 240 rotates between rollers 252, 254, for reasons more apparenthereinafter.

Referring, next, to FIGS. 29 to 34, the bag end folder includes a bottombag wall engaging plate, generally designated 270, having a bottom wall272, and a side wall 274, sloping upwardly in the direction of bagtravel through the machine, and guide 276 curving downwardly towardbottom wall 272 in the direction of bag travel and then parallel withbottom wall 272. Upper bag wall engaging plate 278 is positioned at theend of guide 276 and extends longitudinally along the path of bag travelfrom the end of guide 276.,Flap-engaging plate 280, sloping downwardlyin the direction of bag travel toward bottom wall 272 is mounted at theend of plate 270 and, as will be more apparent hereinafter, receives thebag with the end partially folded and, with plate 276, doubles thefolded end of the bag onto the bag to form a square, folded closure atthe bag end. 1

Referring to FIGS. 14c and 35, rollers 282', 284, having roughened orknurled surfaces are fixed, respectively, to shafts-286, 288. Roller 282is urged toward roller 284 by spring 285, Gears 290, 292, keyed toshafts 286, 288, respectively, intermesh and are driven by. chain 294and sprocket 296 keyed to shaft 288. As will be later described and asshown in FIG. 36, after passing between rollers 282, 284, the square,folded closure at the bag end is flat and ready to receive the closuretape.

As shown in FIGS. 14c and 15b, the tape applicator generally designated40, is mounted at the discharge end of the machine. Referring to FIG.37, tape'applicator 40 includes frame 300 mounted on machine frame 32and shoes 302, of which there are three, fixed to frame 300. For reasonsmore apparent hereinafter, shoes 302 having heating means, not shown,for heating the shoes and, in turn, heating the tape, as it is fed overthe shoes. Tape guides 304, 306, 308, 310 are fixed, respectively, toplates 312, 314, 316, 318 attached by links 320, 322, 324, 326, toactuator plate 328 mounted for rotation about shaft 330 on frame 300.Referring to FIG. 14c, actuator plate 328 is reciprocated about shaft300 by piston rod 332 of cylinder 334 connected to plate 328 by arm 336.As shown in FIG. 37, tape guides304, 306, 308 310 are retracted and tape340 is against shoes 302. When actuated by piston rod 332 and cylinder334, guides 304, 306, 308, 310 are advanced outwardly, away from shaft330, lifting .tape 340 off of heated shoes 302 for reasons more apparenthereinafter.

Guide roll 342 is mounted for rotation on frame 300. Drag brake 346,urged into engagement with tape 340 on guide roll 342 by spring 346,adjustable by locking nuts 348, is mounted in fixed position on frame300. Knife wheels 350, 352 are fixed to shafts 354, 356 mounted forrotation in frame 300. Intel-meshing gears 358, 360, FIG. 14c, keyed toshafts 354, 356,

respectively, drive knife wheels 354, 356 in the direction of thearrows, FIG. 37. Knife blade 362 is fixed to knife wheel 352. Knifeblade 364, as best shown in FIG. 38, ismounted for reciprocation onknife wheel 350, in knife guide 365, being reciprocated back-and-forth,for purposes more apparent hereinafter, by cylinder 366. As best shownin FIGS. 42, 43 and 44-, knife guide 365 extends downwardly beyond thecutting edge of reciprocating knife blade 364 todepress the trailingedge of the bag, while the applied tape is being cut. As best shown inFIGS. 39 and 40, guide 310 has pins 368, spring urged, by spring 370,into engagement with the surface of tape so that, when guides 304, 306,308, 310 are advanced outwardly, away from shaft 330 to lift tape 340off of heated shoes 302, the ends of pins 368 engage the tape and holdthe tape.

The tape is applied to the folded end of the bag as the bag advancesthrough tape applicator 40. The bag is fed into position at applicator40 by rollers 382, 384. The side of tape 340 which, when the tape isapplied to the bag, will be in contact with the bag paper is coated witha thermoplastic adhesive and, because of the feed and guide arrangementin applicator 40, the uncoated side of tape 340 engages heated shoes302. Thus, the thermoplastic coating is heated from the reverse side oftape 340 so that, when applied to the bag, the coating is soft andtacky.

As the leading edge of the bag enters applicator 40, the cut end of thetape, at knife wheels 350, 352, which are rotating, engages the leadingend of the bag. As best shown in FIGS. 42 and 43, the flat portion ofknife wheels 3 50 and 352 are in opposed position as knife member 362and reciprocating knife 364 cuts the end of the tape on the precedingbag. The leading edge of the following bag, advanced and'positio'ned byrollers 382, 384, is in position, so that the circular portion of theperiphery of knife wheels 350, 352, after the opposing flat portions ofthe wheels pass, engage and feed the bag through applicator 40, pressingthe heated, thermoplastic coated tape into adhesive engagement with thebag and advances the bag between driven, mating feed rollers 390, 392,FIG. 37, which, like rollers 382, 384, feed the bag out of tapeapplicator 40. As the bag is being fed, knife wheels 350, 352 arerotating so that, when the trailing edge of the bag is properlypositioned, knife guide 365 on knife wheel 350 depresses the trailingedge. The tape is then cut by reciprocating knife 364. Mating feedrollers 390, 392 are identical to feed rollers 382, 384 and, in additionto feeding the sealed, folded and taped end bag, press the tape intoadhesive contact with the bag. The thermoplastic adhesive on the tape iscooled as it passes between rollers 382, 384 to assist in holding thetape to the bag. The bags, as discharged from rollers 382, 384 arecomplete.

In the operation of the apparatus of the instant application, the bagblanks are formed on conventional tubing equipment. The ply sheets,suitably coated, are superimposed, folded, longitudinally seamed and cutinto the desired lengths. In superimposing the ply sheets, thewater-resistant adhesive is ap plied in the above described pattern ofdots and blocks and the sheets are adhesively secured together.

The adhesive pattern of dots and blocks is, of course, applied at therequired locations and distances from the bottom edge of the bag blanks.

The bag blanks are fed, one by one, through the apparatus of the instantinvention, from the left to right of FIGS. 140, 14c and 15a, 1512, withthe bottom edge of the bag to be heated, sealed, folded and taped at thebottom of the apparatus as shown in FIGS. 14a and 14b; Preferably, infeeding the bags through the apparatus, the bags are spaced with theleading edge of one bag away from the trailing edge of the preceding bagby at least inch.

As the bags are advanced through. the apparatus, upper heater head 102and lower heater head are in the position shown in FIG. 17 so that, asthe end of the: bag passes between heat sinks 104, 122, thethermoplastic material on the inner surface of the inner ply is heatedto-a temperature so that the thermoplastic coating is soft and tacky.The heat required to elevate the temperature of such coating,through thethickness of the plies would, if the bags remained stationary in heatersection 34, cause the bags to burn. In order to eliminate such burningshould it be necessary to stop the machine with bags in heater section34, heater heads 102, 120 are mounted for rotation about shafts 116,134, in the manner hereinbefore described, and, by actuating cylinderand piston 142 heater heads I02, 120 may be moved away from the bagshould the apparatus stop or become jammed. Cylinder 140 may be actuatedautomatically or, manually by the operator.

With the apparatus in operation, heater heads 102, 120 in the positionshown in FIG. 17 and the portion of the bags between heat sinks 104, 122heated, the bags are advanced out of heater section 34 into sealingsection 36. In the apparatus, heat sinks 104, 122, in heater section 34,are aligned with pressure wheels 178, and sealing wheels 182, 184 sothat the outer rounded surface 196 of the intermediate element 194 onsealing wheels 182, 184 contact and compress the plies in the area wherethe thermoplastic coating on the inner surface of the inner plies hasbeen heated and softened by heat sinks 104, 122. Thus, the coating onthe inner surface of the inner ply is sealed along band a, FIGS. 28, 36,41.

With the inner ply sealed along band a, the bag then passes betweenendless belts 210, 212, belts 210, 212 compressing the plies together,holding the heated thermoplastic coating along the inner plies at theband a in contact with each other until the thermoplastic materialcools, hardens and the seal formed along the band a hardens or is cured.The bag then passes between rollers 240, 252, 254 where the end of thebag is embossed along the line where the bag is to be folded. As

best shown in H0. 28 the embossing line, designated b, is spaced fromseal a so that, when folded along embossed line b, seal a will be in thefolded, flap portion of the bag spaced upwardly, on the flap, from thefold line. After the bag end is embossed along fold line b, the end ofthe bag passes into folding section 38. The bottom of the bag, betweenembossed line b and the bag end advances up the sloping portion ofsidewall 274 of plate 270 folding the flap upwardly and backwardly ontothe upper surface of the bag. Plate 278 folds the bag, along embossedline b, against sidewall 274 so that, when folded over into its finalposition by flap-engaging plate 280, the flap is of uniform heightacross the width of the bag and the bag end is square. The bag end, withthe inner ply sealed and the end folded, then moves into rollers 282,284 which compress the flap and feed the bag to tape applicator 40 sothat the leading edge of the bag is in position to engage the cut end ofthe tape in applicator 4i) and to be engaged by knife wheels 250, 252 asthe wheels rotate.

The tape is applied to the end of the bag as hereinabove described and,when discharged from the end of the apparatus by feed rollers 390, 392,tape 340 is applied and adhesively secured to the flap end of the bag asbest shown in FIG. 41. While the machine is run, bags are being fedthrough the machine and tape is being applied, tape guides 304, 306, 308

and 310 are in the position shown in FIG. 37. If, during the operationof the machine, feed of the bags is stopped, tape guides 304, 306, 308,310 are actuated outwardly away from shaft 330 to avoid overheating oftape 340 and over-softening of the thermoplastic adhesive thereon.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of exeluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible.

We claim:

1. A multi-ply paper bag having a thermoplastic coating on the innersurface of the innermost ply, a flap at the bottom of said bag extendingacross the bottom thereof and forming a closure therefor, said flapextending from one side edge of said bag to the other side edge and fromthe bottom of said bag,

when said bag is laid flat, up one sidewall of said bag and a tapeacross said flap adhesively secured to said flap and to said onesidewall of said bag, said tape covering the ply ends in said flap, saidthermoplastic coating on the inner surface of the innermost ply on theopposite sidewalls of said bag in said flap being joined to form a sealalong a line extending across said bag in said flap from one side edgeof said bag to the other side ujge.

2. A multi-ply paper bag, as recited in claim 1, in which said inner plyis joined to an outer ply by a water-resistant adhesive along a line insaid flap.

3. A multi-ply paper bag, as recited in claim 2, in which said line ofwater-resistant adhesive is discontinuous.

4. A multi-ply paper bag, as recited in claim 3, in which the outersurface of the outer ply is water repellent.

5. A multi-ply paper bag, as recited in claim 4, in which saidthermoplastic coating of the inner surface of the innermost ply ispolyethylene.

6. A two-ply gusseted paper bag having an outer ply and an inner ply, athermoplastic coating-on'the inner surface of the inner ply, a flap atthe bottom of said bag extending across the bottom thereof and forming aclosure therefor, said flap extending from one side edge of said bag tothe other side edge and from the bottom of said bag, when said bag islaid flat, up one sidewall of said bag and a tape across said flapadhesively secured to said flap-and to said one sidewall of said bag,said tape covering the ply ends in said flap, said thermoplastic coatingon the inner surface of the inner ply on the opposite sidewalls of saidbag in said flap being joined to form a seal along a line extendingacross said bag in said flap from one side edge of said bag to the otherside edge. i

7. A multi-ply paper bag, as recited in claim 6, in which said inner plyis joined to an outer ply by a water-resistant adhesive along a line insaid flap.

8. A multiply paper bag, as recited in claim 7, in which said line ofwater-resistant adhesive is discontinuous.

9. A multi-ply paper bag, as recited in claim 8, in which the outersurface ofthe outer ply is water repellent.

10. A multi-ply paper bag, as recited in claim 9, in which saidthermoplastic coating of the inner surface of the inner ply ispolyethylene.

1. A multi-ply paper bag having a thermoplastic coating on the innersurface of the innermost ply, a flap at the bottom of said bag extendingacross the bottom thereof and forming a closure therefor, said flapextending from one side edge of said bag to the other side edge and fromthe bottom of said bag, when said bag is laid flat, up one sidewall ofsaid bag and a tape across said flap adhesively secured to said flap andto said one sidewall of said bag, said tape covering the ply ends insaid flap, said thermoplastic coating on the inner surface of theinnermost ply on the opposite sidewalls of said bag in said flap beingjoined to form a seal along a line extending across said bag in saidflap from one side edge of said bag to the other side edge.
 2. Amulti-ply paper bag, as recited in claim 1, in which said inner ply isjoined to an outer ply by a water-resistant adhesive along a line insaid flap.
 3. A multi-ply paper bag, as recited in claim 2, in whichsaid line of water-resistant adhesive is discontinuous.
 4. A multi-plypaper bag, as recited in claim 3, in which the outer surface of theouter ply is water repellent.
 5. A multi-ply paper bag, as recited inclaim 4, in which said thermoplastic coating of the inner surface of theinnermost ply is polyethylene.
 6. A two-ply gusseted paper bag having anouter ply and an inner ply, a thermoplastic coating on the inner surfaceof the inner ply, a flap at the bottom of said bag extending across thebottom thereof and forming a closure therefor, said flap extending fromone side edge of said bag to the other side edge and from the bottom ofsaid bag, when said bag is laid flat, up one sidewall of said bag and atape across said flap adhesively secured to said flap and to said onesidewall of said bag, said tape covering the ply ends in said flap, saidthermoplastic coating on the inner surface of the inner ply on theopposite sidewalls of said bag in said flap being joined to form a sealalong a line extending across said bag in said flap from one side edgeof said bag to the other side edge.
 7. A multi-ply paper bag, as recitedin claim 6, in which said inner ply is joined to an outer ply by awater-resistant adhesive along a line in said flap.
 8. A multiply paperbag, as recited in claim 7, in which said line of water-resistantadhesive is discontinuous.
 9. A multi-ply paper bag, as recited in claim8, in which the outer surface of the outer ply is water repellent.
 10. Amulti-ply paper bag, as recited in claim 9, in which said thermoplasticcoating of the inner surface of the inner ply is polyethylene.